Timothy Vandervoet Abstracts
Timothy Vandervoet
Ph.D. Candidate
Entomology & Insect Science GIDP
Second International Whitefly Symposium
Arusha, Tanzania
February 14-19, 2016
Abstract
The Sweetpotato whitefly, (Bemisia tabaci Middle East Asia Minor 1) is a key pest in the Arizona cotton system that reduces lint quality. Whiteflies are currently managed within an Integrated Pest Management (IPM) framework that involves frequent sampling, action thresholds, and the use of selective chemistries that preserve natural enemy abundance. This program has successfully reduced insecticide use and helped preserve lint quality in Arizona, but uses a pest-centric sampling system that does not explicitly consider natural enemies in decision-making. In this same system, a suite of arthropod predators is known to regulate whitefly populations under certain circumstances. Incorporating the effects of these natural enemies in decision-making has the potential to reduce, delay, or optimize insecticide applications. Improved insecticide use can increase economic gains, minimize human and environmental health risks, and foster better pest management. With over three years of field trials and commercial validations we have identified and estimated predator : prey ratios that indicate the level at which biological control functions, relative to the whitefly action threshold. Without added sampling costs, pest managers can use these ratios to measure and incorporate biological control into whitefly spray decisions. Leveraging this research, we deployed an Extension program that works directly with Pest Control Advisors (PCAs) in the Arizona and California cotton systems through a series of workshops, Extension meetings, and commercial demonstrations to promote the adoption of predator : prey ratios in decision-making. Our efforts focus on usability, validation and demonstration while advancing the core IPM concept of Integrated Control, as proposed by Stern et al. (1959).
Abstract for Lay Audience
The Sweetpotato whitefly (Bemisia tabaci) is a common insect pest that feeds on hundreds of plants. It can cause damage by sucking out the nutrients from plants, transmitting viruses between plants, or by expelling a honeydew-like waste that inhibits photosynthesis and decreases yield. Cotton lint covered with this waste can become infested with sooty mold, which decreases its value. Furthermore, cotton mill buying practices may result in the blacklisting of entire growing regions associated with elevated honeydew and sooty mold contamination. This is especially relevant in Arizona, where cotton produced over $700 million in economic activity and supported over 9,000 jobs in in 2011.
Whiteflies are a key pest in Arizona cotton and warrant great scrutiny. They are currently managed here with an Integrated Pest Management (IPM) framework that employs selective insecticides (that kill only a small number of insect species), offers effective sampling and thresholds (to accurately estimate the level of infestation), and encourages conservation of natural enemy arthropods that prey upon insect pests. When arthropod predators are allowed to naturally consume insect pests they can actually help regulate whitefly populations. This important interaction is called conservation biological control (CBC) and occurs naturally, to different degrees, in many agricultural systems. Understanding the effect, or limit, of natural enemies is especially important in situations where their populations are knocked down by the application of broad-spectrum insecticides targeting other insect pests. In such scenarios, secondary outbreaks of whiteflies are common, due to the loss of CBC provided by natural enemies. By identifying the level of biological control active in any given field, pest managers can weigh the costs and benefits of any insecticidal applications.
To achieve this goal my research focused on identifying key natural enemies and estimating the ratios of predator: prey that help identify the suppression of whiteflies. However, I have also focused on other facets of whitefly control in cotton. In an attempt to quantify whitefly infestation post-harvest, I have worked with microbiologists to develop a laboratory procedure that quantifies the honeydew and sooty mold on cotton lint. This technique, still in the validation stage, could prove to be useful to cotton mills, gins and farming co-ops interested in measuring the season-long effects of whitefly infestation on a given sample of cotton lint. Further, we have worked to engage cotton growers and pest managers through a Cooperative Extension outreach program. We targeted stakeholders across Arizona, as well as parts of California and Mexico, to implement the predator: prey ratios we calculated. Through a series of Extension meetings, workshops and talks we taught methods of whitefly sampling and the use of predator: prey ratios, gauged stakeholders’ interest in biological control of whiteflies, and their likelihood of adoption.
While there is a great deal of research indicating the benefits of conservation biological control, there are very few examples that explicitly incorporate natural enemies into decision-making. My research does this, and could potentially serve as a template for pest management solutions in different systems. Understanding how to fit the dynamics of complex natural enemy interactions into pest control decisions could be useful in any crop production system or region. The more immediate output of my research will be to provide more informed pest control tools to cotton growers in Arizona, which may reduce or delay insecticidal applications for whiteflies. These changes can decrease costs to growers and increase yields, while reducing human and environmental health risks.